Photovoltaic panel cleaning system

ABSTRACT

In accordance with the present invention, a panel cleaning system is provided. In one aspect, the panel cleaning system includes a storage tank containing pressurized air, first and second linear actuators, and a panel-cleaning device wherein the pressurized air contained in the storage tank operates the first and second actuators and the panel-cleaning device to clean PV panels. A further aspect includes sensors associated with the first and second actuators and panel-cleaning device and configured to scan and detect fluid and debris on the PV panels to be removed. Another aspect provides sensors associated with a panel cleaning system and a programmable controller or processor configured to execute instructions stored in a nontransitory computer-readable medium.

FIELD

The present disclosure relates to a photovoltaic (PV) panel cleaningsystem and more particularly to a modular system for cleaning one ormore PV panels.

BACKGROUND AND SUMMARY

Photovoltaic solar panels use sunlight as a source of energy to generateelectricity. Such panels are prone to soling because of ambientconditions and airborne foreign objects. For example, soiling may becaused by dust, ashes from wildfires, snow, leaves, rain, pollen andother objects or liquids that obstruct sunrays on the panels therebysignificantly reducing electrical energy generated by the panels. Suchreduction of energy generated can be detrimental to the economics ofowning and operating solar panels. Periodic cleaning of the panels isrequired in order to reduce the energy production loss caused bysoiling. Some cleaning approaches include employing robots that useliquids such as detergent or water to clean the panels. Other cleaningapproaches include manually cleaning the panels. Exemplary conventionalcleaning devices are disclosed in U.S. Patent Publication No.2019/0353406 entitled “Device and Method for Automatically Dry CleaningReflective Panels” which published to Simonette on Nov. 21, 2019, andPCT Patent Publication No. WO2019/215756 entitled “Automated System forCleaning of Solar Photovoltaic Panels in Solar Array and Method thereof”which published to Bagalkote on Nov. 14, 2019; both of which areincorporated by reference herein. These traditional approaches areenergy intensive, inefficient, detrimental to the environment, and/orlabor intensive.

In accordance with the present invention, a PV panel cleaning system isprovided. In one aspect, the panel cleaning system includes a storagetank containing pressurized air, first and second linear actuators, anda panel-cleaning device wherein the pressurized air contained in thestorage tank operates the first and second actuators and thepanel-cleaning device to clean PV panels. In another aspect, the panelcleaning system includes a storage tank, first and second linearactuators, and a panel-cleaning device wherein the panel-cleaning deviceincludes one or more nozzles and a wiper blade to clean PV panels. Afurther aspect includes sensors associated with the first and secondactuators and panel-cleaning device and configured to scan and detectfluid and debris on the PV panels to be removed. Another aspect providessensors associated with a panel cleaning system and a programmablecontroller or processor configured to execute instructions stored in anontransitory computer-readable medium. A method of using a panelcleaning system is also provided.

The panel cleaning system according to the present disclosure isadvantageous over conventional panel cleaning systems. For example, thepanel cleaning system includes no rotating parts and consumes no netenergy. That is, cleaning PV panels using the panel cleaning systemallows the PV panels to generate additional electrical energy. A portionof the additional electrical energy generated by the PV panels is usedto operate system. In this way, there is a net energy gain when usingthe panel cleaning system to clean the PV panels. Another benefit of thepanel cleaning system is that it is a low maintenance system without theneed of human involvement for operations. The panel cleaning system isadvantageously modular so that it can be used for a single PV panel orarrays of multiple PV panels. The present system advantageously does notuse liquids such as water (which can undesirably freeze and breakcomponents) to clean the PV panels thereby not voiding roof or panelwarranties.

Additional advantages and features of the present invention can beascertained from the following description and claims taken inconjunction with the appended drawings.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is a schematic representation of a panel cleaning systemaccording to the principles of the present disclosure;

FIG. 2 is a perspective view of first and second actuators and apanel-cleaning device of the panel cleaning system shown in FIG. 1located on a roof of a building;

FIG. 3 is a perspective view of the first actuator shown in FIG. 2;

FIG. 4 is a perspective view of the second actuator shown in FIG. 2;

FIG. 5a is a schematic representation of the first actuator;

FIG. 5b is a schematic representation of the second actuator;

FIG. 6 is a back view of the first and second actuators and thepanel-cleaning system;

FIG. 7a is a front view of the panel-cleaning device;

FIG. 7b is a back view of the panel-cleaning device;

FIG. 8a is a side view of the panel-cleaning system with a wiper bladedeflated;

FIG. 8b is a side view of the panel-cleaning system with the wiper bladeinflated;

FIG. 8c is an enlarged view of the wiper blade indicated as area 8 c inFIG. 8 b;

FIG. 9 is a functional block diagram showing components of an exemplarypanel cleaning system shown in FIG. 1;

FIG. 10 is a flowchart showing control logic employed in the panelcleaning system;

FIG. 11 is a schematic representation of another panel cleaning system;

FIG. 12 is a functional block diagram showing components of an exemplarypanel cleaning system shown in FIG. 11;

FIG. 13 is a schematic representation of another panel cleaning system;

FIG. 14 is a schematic representation of an actuator of a panel-cleaningdevice of the panel cleaning system of FIG. 13; and

FIG. 15 is a functional block diagram showing components of an exemplarypanel cleaning system shown in FIG. 13.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

With reference to FIGS. 1, 2 and 9, a photovoltaic (PV) panel cleaningsystem 10 is provided for cleaning a solar panel array 11 (FIG. 2)located on a roof 14 of a building 16. Solar panel array 11 includes PVpanels 12. Cleaning system 10 includes a compressor 18, a storage tank20, a first actuator 22, a second actuator 24, a panel-cleaning deviceor panel-cleaner 26, and a programmable controller or processor 28configured to execute instructions stored in a nontransitorycomputer-readable medium (FIG. 9). Cleaning PV panels 12 using system 10allows PV panels 12 to generate additional electrical energy. A portionof the additional electrical energy generated by panels 12 is used tooperate system 10. In this way, there is a net energy gain when usingsystem 10 to clean panels 12.

As shown in FIG. 1, the compressed air from compressor 18 is dischargedto storage tank 20 (via passageway 30) where it is stored for use.Compressor 18 may be an electric compressor, for example. Compressor 18and storage tank 20 are located remotely from roof 14 of building 16.That is, compressor 18 and storage tank 20 may be housed within a shedor other housing structure, for example, located remotely from roof 14of building 16. Storage tank 20 includes an inlet 32, a first outlet 33,and a second outlet 34. Inlet 32 is in fluid communication withcompressor 18 via passageway 30 so that compressed air discharged fromcompressor 18 flows to inlet 32 of storage tank 20.

First actuator 22 may be located on roof 14 at a first side of panelarray 11 and may be a rodless pneumatic linear actuator. With referenceto FIGS. 1-3, 5 a, and 6, first actuator 22 includes a housing 36, apiston or drive member 40 (FIG. 5a ), and a carriage 42. Piston 40 ismovably disposed within a cavity 44 of housing 36 and separates cavity44 into a first region 46 and a second region 48. Carriage 42 ismechanically connected to piston 40 through a slot 50 formed in housing36 so that carriage 42 and piston 40 move relative to housing 36. Slot50 extends substantially a length of housing 36. In some configurations,carriage 42 may be magnetically connected to piston 40 disposed withinhousing 36 so that carriage 42 and piston 40 move relative to housing36.

As shown in FIG. 3, one or more sensors 49 are coupled to carriage 42and are configured to continuously or intermittingly scan PV panels 12to detect fluid or debris located on PV panels 12 as carriage 42 movesalong PV panels 12. Sensors 49 may be optical sensors, for example, andmay be passive or active optical sensors. This data is communicated tocontroller 28 and used at least in part to determine the cleaning cycleof system 10. Stated differently, movement of piston 40 (and carriage42) may be based at least in part on the data provided by sensors 49.For example, sensors 49 are able to scan and detect the debris size andtype located on PV panels 12. In this way, piston 40 is operated to slowdown or stop at a particular location so that compressed air dischargedfrom panel-cleaning device 26 is directed at the debris until it isremoved from PV panels 12.

Second actuator 24 is located on roof 14 at a second side of panel array11 and may be a rodless pneumatic linear actuator. With reference toFIGS. 1, 2, 4, 5 b, and 6, second actuator 24 includes a housing 52, apiston or drive member 54 (FIG. 5b ), and a carriage 56. Piston 54 ismovably disposed within a cavity 58 of housing 52 and separates cavity58 into a first region 60 and a second region 62. Carriage 56 ismechanically connected to piston 54 through a slot 63 formed in housing52 so that carriage 56 and piston 54 move relative to housing 52. Slot63 extends substantially a length of housing 52. In some configurations,carriage 56 may be magnetically connected to piston 54 disposed withinhousing 52 so that carriage 56 and piston 54 move relative to housing52.

As shown in FIG. 4, one or more sensors 59 are coupled to carriage 56and are configured to continuously or intermittingly scan PV panels 12to detect fluid or debris located on PV panels 12 as carriage 56 movesalong PV panels 12. Sensors 59 may be optical sensors, for example, andmay be passive or active optical sensors. This data is communicated tocontroller 28 and used at least in part to determine the cleaning cycleof system 10. Stated differently, movement of piston 54 (and carriage56) may be based at least in part on the data provided by sensors 59.For example, sensors 59 are able to scan and detect the debris size andtype located on PV panels 12. In this way, piston 54 is operated to slowdown or stop at a particular location so that compressed air dischargedfrom panel-cleaning device 26 is directed at the debris until it isremoved from PV panels 12.

As shown in FIG. 1, a first fluid passageway 64 extends from firstoutlet 33 of storage tank 20 to an inlet 66 of a 3-way valve 67. Asecond fluid passageway 68 extends from a first outlet 70 of 3-way valve67 to a first inlet 69 of housing 36 of first actuator 22. A firstsensor 65 is disposed along second fluid passageway 68 upstream of firstinlet 69 of the housing 36 and is configured to measure an operatingparameter indicative of a pressure of the compressed air flowing throughsecond fluid passageway 68. This data is communicated to controller 28and used at least in part to determine the cleaning cycle of system 10.First sensor 65 may be a pressure sensor such as a pressure gauge orpressure transducer, for example. A third fluid passageway 72 extendsfrom a second outlet 73 of 3-way valve 67 to a second inlet 74 ofhousing 36 of first actuator 22. A second sensor 71 is disposed alongthird fluid passageway 72 upstream of second inlet 74 of the housing 36and is configured to measure an operating parameter indicative of apressure of the compressed air flowing through third fluid passageway72. This data is communicated to controller 28 and used at least in partto determine the cleaning cycle of system 10. Second sensor 71 may be apressure sensor such as a pressure gauge or pressure transducer, forexample.

As shown in FIG. 5a , a first valve 76 is associated with first inlet 69of housing 36 and is movable between an open position in whichcompressed air flowing through second fluid passageway 68 is allowed toflow to first region 46 of housing 36, and a closed position in whichcompressed air flowing through second fluid passageway 68 is preventedfrom flowing to first region 46. First valve 76 may be disposed withinfirst inlet 69. Similarly, a second valve 78 is associated with secondinlet 74 of housing 36 and may be movable between an open position inwhich compressed air flowing through third fluid passageway 72 isallowed to flow to second region 48 of housing 36, and a closed positionin which compressed air flowing through third fluid passageway 72 isprevented from flowing to second region 48. Second valve 78 may bedisposed within second inlet 74. It will be appreciated that first andsecond valves 76, 78 could be electromagnetic, solenoid-activatedvalves, for example.

As shown in FIG. 1, a first fluid line 80 extends from second fluidpassageway 68 at a location between 3-way valve 67 and first valve 76 toa first inlet 82 of housing 52 of second actuator 24. A third sensor 81is disposed along first fluid line 80 upstream of first inlet 82 of thehousing 52 and is configured to measure an operating parameterindicative of a pressure of the compressed air flowing through firstfluid line 80. This data is communicated to controller 28 and used atleast in part to determine the cleaning cycle of system 10. Third sensor81 may be a pressure sensor such as a pressure gauge or pressuretransducer, for example. A second fluid line 84 extends from third fluidpassageway 72 at a location between 3-way valve 67 and second valve 78to a second inlet 85 of housing 52. A fourth sensor 83 is disposed alongsecond fluid line 84 upstream of second inlet 85 of housing 52 and isconfigured to measure an operating parameter indicative of a pressure ofthe compressed air flowing through second fluid line 84. This data iscommunicated to controller 28 and used at least in part to determine thecleaning cycle of system 10. Fourth sensor 83 may be a pressure sensorsuch as a pressure gauge or pressure transducer, for example.

As shown in FIG. 5b , a third valve 86 is associated with first inlet 82of housing 52 and is movable between an open position in whichcompressed air flowing through first fluid line 80 is allowed to flow tofirst region 60 of housing 52, and a closed position in which compressedair flowing through first fluid line 80 is prevented from flowing tofirst region 60. Third valve 86 may be disposed within first inlet 82.Similarly, a fourth valve 88 is associated with second inlet 85 ofhousing 52 and may be movable between an open position in whichcompressed air flowing through second fluid line 84 is allowed to flowto second region 62 of housing 52, and a closed position in whichcompressed air flowing through second fluid line 84 is prevented fromflowing to second region 62. Fourth valve 88 may be disposed withinsecond inlet 85. It will be appreciated that third and fourth valves 86,88 could be solenoid valves, for example.

With reference to FIG. 1, 7, 8 a, 8 b, panel-cleaning device 26 includesa carriage 90, one or more nozzles or outlet slots 91 (FIG. 1), and anoptional wiper blade 92 (FIGS. 7a, 8a, and 8b ). Panel-cleaning device26 may be an air knife which generates high intensity airflow to blowoff liquid and debris from the PV panels 12. Carriage 90 has a first end93 a that is mechanically coupled to sliding carriage 42 of firstactuator 22, which engages a C-shaped track of housing 36 and a secondend 93 b that is mechanically coupled to sliding carriage 56 of secondactuator 24, which engages a C-shaped track of housing 52. That is,first end 93 a is positioned on and supported by a top surface ofcarriage 42 and is coupled to carriage 42 via fasteners (e.g., screws,bolts, and/or rivets) extending through a lower surface of first end 93a and the top surface of carriage 42. Similarly, second end 93 b ispositioned on and supported by a top surface of carriage 56 and iscoupled to carriage 56 via fasteners (e.g., screws, bolts, and/orrivets) extending through a lower surface of second end 93 b and the topsurface of carriage 56 (FIG. 6). In this way, movement of pistons 40, 54of actuators 22, 24, respectively, also moves carriage 90 along panelarray 11. In some configurations, first end 93 a is magnetically coupledto carriage 42 and second end 93 b is magnetically coupled to carriage56. That is, a first magnet is coupled to the lower surface of first end93 a and a second magnet is coupled to the top surface of carriage 42.In this way, the first magnet produces a magnetic force urging thesecond magnet towards it thereby coupling first end 93 a and carriage 42to each other. Similarly, a third magnet is coupled to the lower surfaceof second end 93 b and a fourth magnet is coupled to the top surface ofcarriage 56. In this way, the third magnet produces a magnetic forceurging the fourth magnet towards it thereby coupling second end 93 b andcarriage 56 to each other. Alternatively, a first magnet can be locatedat the top surface of carriage 42 and magnetic material at the bottomsurface of the end 93 a, and a second magnet can be located at the topsurface of carriage 56 and magnetic material at the lower surface of theend 93 b.

One or more sensors 97 are coupled to carriage 90 and are configured tocontinuously or intermittingly scan PV panels 12 to detect fluid ordebris located on PV panels 12 as carriage 90 moves along PV panels 12.Sensors 97 may be optical sensors, for example, disposed along a lengthof carriage 90, and may be passive or active optical sensors. This datais communicated to controller 28 and used at least in part to determinethe cleaning cycle of system 10. Stated differently, movement of pistons40, 54 may be based at least in part on the data provided by sensors 97.For example, sensors 97 are able to scan and detect the debris size andtype located on PV panels 12. In this way, pistons 40, 54 are operatedto slow down or stop at a particular location, so that compressed airdischarged from nozzles 91 is directed at the debris until it is removedfrom PV panels 12.

As shown in FIG. 1, a manifold 96 is associated with the carriage 90 andincludes an inlet 98 and a plurality of outlets 100. That is, manifold96 can be disposed within carriage 90, for example. A fluid passageway102 extends from second outlet 34 of storage tank 20 to inlet 98 ofmanifold 96. A valve 104 is disposed along fluid passageway 102 and ismovable between an open position in which compressed air flowing throughfluid passageway 102 is allowed to flow to manifold 96, and a closedposition in which compressed air flowing through fluid passageway 102 isprevented from flowing to manifold 96.

Each nozzle 91 is in fluid communication with a respective outlet 100 ofmanifold 96. Each nozzle 91 is also configured to entrain surroundingcompressed air and direct the compressed air to the panel array 11 toclean the PV panels 12. Each nozzle 91 is designed and positioned suchthat nozzles 91 clean fluid or debris such as dirt, pollen, or dust, forexample, located on panels 12 without touching panels 12. That is, eachnozzle 91 is spaced apart from panels 12 approximately 1-5 millimeters(mm). As shown in FIG. 7b , nozzles 91 generate a uniform sheet oflaminar airflow to blow off liquid and debris from the PV panels 12. Theuniform sheet of laminar airflow discharged from nozzles 91 attaches toa surface of the PV panels 12 using the Coandă effect.

The pressure of compressed air discharged from each nozzle 91 is lowerthan the pressure of compressed air stored in storage tank 20. Thepressure and flow rate of compressed air discharged from each nozzle 91are controlled so that maximum cleaning efficiency of the panels 12 isachieved for a particular location. That is, the pressure and flow rateof compressed air discharged from each nozzle 91 are controlled based inpart on the debris size and type and ambient conditions (e.g., ambienttemperature and humidity). In some configurations, a heating element maybe located along fluid passageway 102 to heat compressed air flowingtherethrough. In this way, the compressed air discharged from eachnozzle 91 is able to melt ice or snow that has accumulated on panels 12.

A fluid line 105 extends from fluid passageway 102 to an inlet 106 ofwiper blade 92. In some configurations, fluid line 105 extends fromstorage tank 20 to wiper blade 92. A valve 108 is associated with inlet106 of wiper blade 92 and is movable between an open position in whichcompressed air flowing through fluid line 105 is allowed to flow towiper blade 92, and a closed position in which compressed air flowingthrough fluid line 105 is prevented from flowing to wiper blade 92.Valve 108 can be disposed within inlet 106, for example.

With reference to FIGS. 7a, 7b, 8a, and 8b , wiper blade 92 is removablycoupled to and supported by a leading edge 107 of carriage 90 andextends substantially a length of carriage 90. In some configurations,wiper blade 92 can be removably coupled to carriage 90 via fasteners. Inother configurations, wiper blade 92 can be removably coupled tocarriage 90 via adhesive attachment means. Wiper blade 92 is also madeof an inflatable material. In some configurations, wiper blade 92 ismade of polyvinyl chloride (PVC), urethane, textile reinforced urethaneplastic, rubber, thermoplastic or polyurethane, for example. Wiper blade92 is operable between a first state (inflated state) in whichcompressed air flows to a cavity 109 of wiper blade 92 to inflate wiperblade 92, and a second state (deflated state) in which compressed air ispurged from wiper blade 92. When wiper blade 92 is in the first state,an outer surface 110 of wiper blade 92 contacts PV panels 12. In thisway, wiper blade 92 is able to remove debris located on the PV panels 12as carriage 90 moves along PV panels 12. When wiper blade 92 is in thesecond state, valve 108 purges compressed air within cavity 109 toambient surroundings thereby causing wiper blade 92 to deflate andbecome spaced apart from PV panels 12

Outer surface 110 of hollow wiper blade 92 is coated with micro fabrics111 to provide for a soft and flexible contact between wiper blade 92and PV panels 12. In some configurations, only a portion of hollow wiperblade 92 that comes in contact with PV panels 12 is coated with microfabrics 111. Micro fabrics 111 can be made of compositions of polyesterand polyamide. For example, micro fabrics 111 can be 80% polyester and20% polyamide, 50% polyester and 50% polyamide, or 90% polyester and 10%polyamide. Micro fabrics 111 have a thickness in the range of 1-20 mm,more preferably 2-5 mm, deposited on outer surface 110 of wiper blade92. Micro fabrics 111 are glued (laminated with glue and heat) on wiperblade 92. Optionally, micro fabrics 111 can be attached with clips orother fastening mechanisms on wiper blade 92.

As shown in FIG. 9, controller 28 is in communication with compressor18, actuators 22, 24, panel-cleaning device 26, valves 67, 76, 78, 86,88, 104, 108, sensors 49, 59, 65, 71, 81, 83, 97, and an inverter 113.Controller 28 can control operation of compressor 18, actuators 22, 24and device 26, and can open and close valves 67, 76, 78, 86, 88, 104,108.

A mobile device 114 (e.g., a tablet, a smartphone, a laptop, or othersimilar device) includes a processor that is configured to executeinstructions stored in a nontransitory computer-readable medium, such asa read-only memory (ROM) and/or random-access memory (RAM). Mobiledevice 114 includes a software application 116. The functions of thesoftware application 116 is accessed using, for example, nativeapplication editions of the software and/or web applications of thesoftware. Mobile device 114 and controller 28 are configured to, usingthe software application 116, communicate via wireless communicationprotocol, which includes an internet, Wi-Fi, Bluetooth®, or cellularconnection or any other wireless communication protocol, for example. Inthis way, a user may control operations of system 10 using mobile device114.

With reference to FIG. 10, a flowchart illustrating exemplary softwarecontrol logic 200 is shown. Control logic 200 begins at 204 when thesystem 10 is activated. The system 10 may be activated, for example, inresponse to 1) inverter 113 indicating a predetermined thresholddecrease in electricity generation, 2) an operator sending a cleaningcommand to controller 28 via mobile device 114, 3) one or more sensors49, 59, 65, 71, 81, 83, 97 detecting fluid or debris on panel array 11,or 4) a preset schedule to clean panel array 11.

At 208, control logic 200 determines, using controller 28, whether wiperblade 92 needs to be inflated. For example, wiper blade 92 may need tobe inflated to remove certain fluid or debris detected by sensors 49,59, 97. In another example, the operator may select an option to inflatewiper blade 92 when sending the cleaning command to controller 28 viamobile device 114. If so, control logic 200 proceeds to 212; otherwise,control logic 200 proceeds to 216. At 212, control logic 200 provides,using controller 28, compressed air from storage tank 20 to wiper blade92. That is, controller 28 moves valve 108 from the closed position tothe open position. In this way, compressed air from storage tank 20flows to wiper blade 92 so that wiper blade 92 is inflated.

At 216, control logic 200 provides, using controller 28, compressed airfrom storage tank 20 to actuators 22, 24. For example, to clean an upperportion of panel array 11, valves 67, 78, 88 are each moved from theclosed position to the open position and valves 76, 86 are each movedfrom the open position to the closed position, so that compressed airfrom storage tank 20 flows to regions 48, 62 of actuators 22, 24,respectively, thereby exerting a force on pistons 40, 54 to causepistons 40, 54 and panel-cleaning device 26 to move in a seconddirection Y2 along panel array 11. Compressed air contained in regions46, 60 of actuators 22, 24 are purged to ambient surroundings. It isunderstood that valves 67, 76, 78, 86, 88 may be moved simultaneously orin a sequence (e.g., moving valves 76, 86 to the closed position, thenmoving valve 67 to the open position, and finally moving valves 78, 88to the open position).

To clean a lower portion of panel array 11, valves 67, 76, 86 are eachmoved from the closed position to the open position and valves 78, 88are each moved from the open position to the closed position, so thatcompressed air from storage tank 20 flows to regions 46, 60 of actuators22, 24, respectively, thereby exerting a force on pistons 40, 54 tocause pistons 40, 54 and panel-cleaning device 26 to move in a firstdirection Y1 along panel array 11. Compressed air contained in regions48, 62 of actuators 22, 24 are purged to ambient surroundings. It isunderstood that valves 67, 76, 78, 86, 88 may be moved simultaneously orin a sequence (e.g., moving valves 78, 88 to the closed position, thenmoving valve 67 to the open position, and finally moving valves 76, 86to the open position).

At 220, control logic 200 determines, using controller 28, whether thespeed of panel-cleaning device 26 needs to be adjusted. For example,data obtained via one or more sensors 49, 59, 65, 71, 81, 83, 97 iscommunicated to controller 28 so that controller 28 can increase ordecrease speed of panel-cleaning device 26. That is, if sensors 49, 59,97 detect heavy debris on panels 12 then the speed of panel-cleaningdevice 26 may be decreased. If sensors 49, 59, 97 detect little or nodebris on panels 12 then the speed of panel-cleaning device 26 may beincreased. If so, control logic 200 proceeds to 224; otherwise, controllogic 200 proceeds to 228.

At 224, control logic 200 adjust, using controller 28, the position ofvalves 78, 88 to increase or decrease the speed of panel-cleaning device26 in a second direction Y2 along panel array 11, or the position ofvalves 76, 86 to increase or decrease the speed of panel-cleaning device26 in a first direction Y1 along panel array 11. At 228, control logic200 provides, using controller 28, compressed air from storage tank 20to nozzles 91. That is, controller 28 moves valve 104 from the closedposition to the open position, so that compressed air from the storagetank 20 flows to nozzles 91 where it is directed to the PV panels 12 toclean the PV panels 12. The control logic 200 then proceeds to 236 andends. The system 10 ends when, for example, a stop command is generatedfrom controller 28. The stop command may be generated based on data fromsensors 49, 59, 65, 71, 81, 83, 97, or based on the ending of thepredetermined cleaning cycle. In some configurations, the stop commandmay be generated based on a system fault detection being activated, oran operator manually stopping the cleaning cycle.

System 10 of the present disclosure provides the benefit of cleaning PVpanels 12 without using rotating parts or liquids such as water. Anotherbenefit of panel cleaning system 10 is that it is a low maintenancesystem without the need of human involvement for operations.

With reference to FIGS. 11 and 12, another system 310 is provided. Thestructure and function of system 310 may be similar or identical tosystem 10 described above, apart from any exception noted below.

As shown in FIG. 11, system 310 includes a compressor 318, a storagetank 320, a first actuator 322, a second actuator 324, a panel-cleaningdevice 326, and a programmable controller or processor 328 (FIG. 12)configured to execute instructions stored in a nontransitorycomputer-readable medium. The structure and function of compressor 318,storage tank 320, first actuator 322, second actuator 324, andpanel-cleaning device 326 may be similar or identical to that ofcompressor 18, storage tank 20, first actuator 22, second actuator 24,and panel-cleaning device 26 respectively, described above, andtherefore, will not be described again in detail.

Panel-cleaning device 326 includes a carriage 390 and a plurality ofnozzles or slots 391. Carriage 390 has a first end 393 a that ismechanically coupled to first actuator 322 and a second end 393 b thatis mechanically coupled to second actuator 324. In this way, movement ofpistons of actuators 322, 324, also moves carriage 390 along panelarray.

Each nozzle 391 is coupled to and supported by carriage 390. Each nozzle391 is designed and positioned such that nozzles 391 clean fluid ordebris such as dirt, pollen, or dust, for example, located on the panelarray without touching the panel array. That is, each nozzle 391 isspaced apart from the panel array.

A first fluid passageway 340 extends from an outlet 342 of storage tank320 to a first nozzle 391 a of nozzles 391. A first valve 343 isdisposed along first fluid passageway 340 and is movable between an openposition in which compressed air flowing through first fluid passageway340 is allowed to flow to first nozzle 391 a, and a closed position inwhich compressed air flowing through first fluid passageway 340 isprevented from flowing to first nozzle 391 a. A second fluid passageway346 extends from first fluid passageway 340 at a location between outlet342 and first valve 343 to a second nozzle 391 b of nozzles 391. Asecond valve 348 is disposed along second fluid passageway 346 and ismovable between an open position in which compressed air flowing throughsecond fluid passageway 346 is allowed to flow to second nozzle 391 b,and a closed position in which compressed air flowing through secondfluid passageway 346 is prevented from flowing to second nozzle 391 b.

A third fluid passageway 350 extends from first fluid passageway 340 ata location between outlet 342 and first valve 343 to a third nozzle 391c of nozzles 391. A third valve 352 is disposed along third fluidpassageway 350 and is movable between an open position in whichcompressed air flowing through third fluid passageway 350 is allowed toflow to third nozzle 391 c, and a closed position in which compressedair flowing through third fluid passageway 350 is prevented from flowingto third nozzle 391 c. As shown in FIG. 12, controller 328 is incommunication with compressor 318, actuators 322, 324, panel-cleaningdevice 326, and valves 348, 343, 352. Controller 328 can controloperation of compressor 318, actuators 322, 324 and device 326, and canopen and close valves 348, 343, 352.

System 310 provides the benefit of allowing the compressed air directedfrom one of nozzles 391 a, 391 b, 391 c to be controlled independentlyof the other nozzles 391 a, 391 b, 391 c. In this way, compressed air isallowed to be focused on a smaller area of panel array that needscleaning.

With reference to FIGS. 13-15, another system 410 is provided. Thestructure and function of system 410 may be similar or identical tosystems 10, 310 described above, apart from any exception noted below.

As shown in FIG. 13, system 410 includes a compressor 418, a storagetank 420, a first actuator 422, a second actuator 424, a panel-cleaningdevice 426, and a programmable controller or processor 428 configured toexecute instructions stored in a nontransitory computer-readable medium(FIG. 15). The structure and function of compressor 418, storage tank420, first actuator 422, and second actuator 424, may be similar oridentical to that of compressor 18, storage tank 20, first actuator 22,and second actuator 24, respectively, described above, and therefore,will not be described again in detail.

Panel-cleaning device 426 includes an actuator 460 and a nozzle 462.With reference to FIGS. 13 and 14, actuator 460 is a rodless pneumaticlinear actuator and includes a housing 463, a piston 464 (FIG. 14), anda carriage 466 (FIG. 13). Housing 463 includes a first end 468mechanically coupled to a carriage of first linear actuator 422 and asecond end 470 mechanically coupled to a carriage of second linearactuator 424. In some configurations, first end 468 may be magneticallycoupled to the carriage of first linear actuator 422 and second end 470may be magnetically coupled to the carriage of second linear actuator424. Piston 464 is movably disposed within a cavity 472 of housing 463and separates cavity 472 into a first region 474 and a second region476. Carriage 466 is mechanically or magnetically connected to piston464 so that carriage 466 and piston 464 move relative to housing 463.

One or more sensors 478 are associated with housing 463 and areconfigured to continuously or intermittingly scan a panel array todetect fluid or debris located on the panel array. Sensors 478 may beoptical sensors, for example, and may be passive or active opticalsensors. This data is communicated to controller 428 and used at leastin part to determine the cleaning cycle of system 410. Stateddifferently, movement of piston 464 (and carriage 466) may be based atleast in part on the data provided by sensors 478. For example, sensors478 are able to scan and detect the debris size and type located on thepanel array. In this way, piston 464 is operated to slow down or stop ata particular location so that compressed air discharged from nozzle 462is directed at the debris until it is removed from the panel array.

A first fluid passageway 430 extends from a first outlet 431 of storagetank 420 to a first inlet 432 of housing 463 of actuator 460. A secondfluid passageway 434 extends from first fluid passageway 430 to a secondinlet 438 of housing 463 of actuator 460. A first valve 440 isassociated with first inlet 432 of housing 463 and is movable between anopen position in which compressed air flowing through first fluidpassageway 430 is allowed to flow to region 476 of housing 463, and aclosed position in which compressed air flowing through first fluidpassageway 430 is prevented from flowing to region 476. First valve 440may be disposed within first inlet 432. Similarly, a second valve 444 isassociated with second inlet 438 of housing 463 and may be movablebetween an open position in which compressed air flowing through secondfluid passageway 434 is allowed to flow to region 474 of housing 463,and a closed position in which compressed air flowing through secondfluid passageway 434 is prevented from flowing to region 474. Secondvalve 444 may be disposed within second inlet 438.

A third valve 448 is disposed along first fluid passageway 430 and ismovable between an open position in which compressed air is allowed toflow through first fluid passageway 430, and a closed position in whichcompressed air is prevented from flowing through first fluid passageway430. A fourth valve 456 is disposed along second fluid passageway 434and is movable between an open position in which compressed air isallowed to flow through second fluid passageway 434, and a closedposition in which compressed air is prevented from flowing throughsecond fluid passageway 434.

Nozzle 462 is coupled to and supported by carriage 466. Nozzle 462 isdesigned and positioned such that nozzle 462 cleans fluid or debris suchas dirt, pollen, or dust, for example, located on the panel arraywithout touching the panel array. That is, nozzle 462 is spaced apartfrom the panel array and directs compressed air to the panel array toclean the panel array. A third fluid passageway 452 extends from asecond outlet 454 of storage tank 420 to nozzle 462. A fifth valve 450is disposed along third fluid passageway 452 and is movable between anopen position in which compressed air flowing through third fluidpassageway 452 is allowed to flow to nozzle 462, and a closed positionin which compressed air flowing through third fluid passageway 452 isprevented from flowing to nozzle 462.

Controller 428 is in communication with compressor 418, actuators 422,424, 460, valves 440, 444, 448, 450, 456, and sensor 478. Controller 428can control operation of compressor 418, actuators 422, 424, 460, andcan open and close valves 440, 444, 448, 450, 456.

Valves 440, 448 are each moved from the closed position to the openposition so that compressed air from storage tank 420 flows to region476 of actuator 460 thereby exerting a force on piston 464 to causepiston 464 and carriage 466 to move in a first lateral direction X1along the panel array. Compressed air contained in region 474 ofactuator 460 is purged to ambient surroundings. Similarly, valves 444,456 are each moved from the closed position to the open position so thatcompressed air from storage tank 420 flows to region 474 of actuator 460thereby exerting a force on piston 464 to cause piston 464 and carriage466 to move in a second lateral direction X2 along the panel array.Compressed air contained in region 476 of actuator 460 is purged toambient surroundings.

System 410 provides the benefit of allowing nozzle 462 to move laterallyalong the panel array. In this way, compressed air is allowed to befocused on a smaller area of the panel array that needs cleaning.

While various embodiments have been disclosed, other variations areenvisioned. For example, linear actuators 22, 24 may be single actingactuators as opposed to double acting actuators. Furthermore, actuator22 may be replaced with a rail and sliding guide member and the slidingguide member may be attached to panel-cleaning device 26. In this way,the sliding guide member may slide along the rail when actuator 24 movesthe panel-cleaning device 26 along panel array 11. It is also envisionedthat the PV panels may be supported within frames which have postsmounted to the ground, or which are mounted on top of a vehicle parkingroof or the like, or floating on water instead of the roof mountingillustrated, such that the present cleaning apparatus is mounted to sucha frame or associated peripherally located structure. Furthermore, ablower can be used to run the nozzles for cleaning the PV panels insteadof compressed air from the storage tank. Furthermore, features from oneembodiment can be interchanged with features of another embodimentdisclosed hereinabove, and the claims can be multiply dependent on eachother in any combination. Variations are not to be regarded as adeparture from the present disclosure, and all such modifications areintended to be included within the scope and spirit of the presentinvention.

The invention claimed is:
 1. A system for cleaning photovoltaic panels,the system comprising: a storage tank containing pressurized air; afirst linear actuator located at a first side of the photovoltaic panelsand in fluid communication with the storage tank, the first linearactuator including a first housing and a first piston moveably disposedin the first housing; a second linear actuator located at a second sideof the photovoltaic panels and in fluid communication with the storagetank, the second linear actuator including a second housing and a secondpiston moveably disposed in the second housing; and a panel-cleaner influid communication with the storage tank and coupled to the firstpiston and the second piston, the panel-cleaner directing pressurizedair from the storage tank to the photovoltaic panels to clean thephotovoltaic panels.
 2. The system of claim 1, further comprising: afirst carriage coupled to the first piston; a second carriage coupled tothe second piston; a sensor associated with one of the first and secondcarriages and configured to detect objects or fluid located on thephotovoltaic panels; and a controller configured to execute programmedinstructions stored in a nontransitory computer-readable medium, whereinthe instructions include: (i) obtaining data indicative of objects orfluid located on the photovoltaic panels from the sensor; and (ii)automatically operating the first and second linear actuators and thepanel-cleaner in response to the sensor detecting objects or fluid onthe photovoltaic panels.
 3. The system of claim 2, further comprising aremote mobile transmitter in communication with the controller andconfigured to send a cleaning command to the controller to execute theinstructions.
 4. The system of claim 1, further comprising: a firstcarriage coupled to the first piston; a second carriage coupled to thesecond piston; a first sensor associated with the first carriage andconfigured to detect objects or fluid located on the photovoltaicpanels; a second sensor associated with the second carriage andconfigured to detect objects or fluid located on the photovoltaicpanels; a controller configured to execute programmed instructionsstored in a nontransitory computer-readable medium, wherein theinstructions include: (i) obtaining data indicative of objects or fluidlocated on the photovoltaic panels from the first and second sensors;and (ii) automatically operating the first and second linear actuatorsand the panel-cleaner in response to at least one of the first andsecond sensors detecting objects or fluid on the photovoltaic panels. 5.The system of claim 4, wherein the first and second sensors are opticalsensors.
 6. The system of claim 1, wherein the panel-cleaner includes anair knife.
 7. The system of claim 1, further comprising: a first fluidpassageway in fluid communication with the storage tank and the firstlinear actuator, and providing pressurized air from the storage tank tothe first linear actuator to move the first piston; a second fluidpassageway in fluid communication with the storage tank and the secondlinear actuator, and providing pressurized air from the storage tank tothe second linear actuator to move the second piston; and a third fluidpassageway in fluid communication with the storage tank and thepanel-cleaner, and providing pressurized air from the storage tank tothe panel-cleaner to clean the photovoltaic panels.
 8. The system ofclaim 7, wherein the panel-cleaner further includes a manifold in fluidcommunication with the third fluid passageway and a plurality ofnozzles, and wherein the plurality of nozzles direct pressurized airflowing through the third fluid passageway and the manifold to thephotovoltaic panels to clean the photovoltaic panels.
 9. The system ofclaim 1, wherein the panel-cleaner includes: a housing defining a cavityand having a first end coupled to the first piston and a second endcoupled to the second piston; a carriage movably coupled to the housing;and a nozzle coupled to the carriage, wherein the nozzle directspressurized air from the storage tank to the photovoltaic panels toclean the photovoltaic panels.
 10. The system of claim 9, furthercomprising: a first fluid passageway in fluid communication with thestorage tank and a first region of the cavity of the housing, the firstfluid passageway providing pressurized air from the storage tank to thefirst region to move the carriage and the nozzle in a first lateraldirection; a second fluid passageway in fluid communication with thestorage tank and a second region of the cavity of the housing, thesecond fluid passageway providing pressurized air from the storage tankto the second region to move the carriage and the nozzle in a secondlateral direction; and a third fluid passageway in fluid communicationwith the storage tank and the nozzle, the third fluid passagewayproviding pressurized air from the storage tank to the nozzle.
 11. Thesystem of claim 1, further comprising: a first fluid passageway in fluidcommunication with the storage tank and a first nozzle of thepanel-cleaner, and providing pressurized air from the storage tank tothe first nozzle; and a second fluid passageway in fluid communicationwith the storage tank and a second nozzle of the panel-cleaner, andproviding pressurized air from the storage tank to the second nozzle.12. The system of claim 11, further comprising: a first valve disposedalong the first fluid passageway and movable between an open position inwhich pressurized air is allowed to flow through the first fluidpassageway and a closed position in which pressurized air is preventedfrom flowing through the first fluid passageway; and a second valvedisposed along the second fluid passageway and movable between an openposition in which pressurized air is allowed to flow through the secondfluid passageway and a closed position in which pressurized air isprevented from flowing through the second fluid passageway.
 13. Thesystem of claim 1, wherein the panel-cleaner includes a wiper blade thatis in fluid communication with the storage tank, and wherein the wiperblade is operable between a first state in which compressed air from thestorage tank inflates the wiper blade so that the wiper blade contactsthe photovoltaic panels, and a second state in which compressed air ispurged from the wiper blade so that the wiper blade is spaced apart fromthe photovoltaic panels.
 14. A system for cleaning photovoltaic panels,the system comprising: (a) a storage tank containing compressed air; (b)a first actuator located at a first side of the photovoltaic panels andincluding a first housing and a first drive member at least partiallydisposed in the first housing and movable relative to the first housing;(c) a second actuator located at a second side of the photovoltaicpanels and including a second housing and a second drive member at leastpartially disposed in the second housing and movable relative to thesecond housing; and (d) a panel-cleaner in fluid communication with thestorage tank and coupled to the first drive member and the second drivemember, the panel-cleaner directing compressed air from the storage tankto the photovoltaic panels to clean the photovoltaic panels.
 15. Thesystem of claim 14, wherein the first and second actuators are rodlesspneumatic actuators.
 16. The system of claim 14, wherein thepanel-cleaner includes a plurality of nozzles in fluid communicationwith the storage tank, and wherein the plurality of nozzles generate auniform sheet of laminar airflow to the photovoltaic panels to clean thephotovoltaic panels.
 17. The system of claim 16, wherein the pluralityof nozzles are spaced apart from the photovoltaic panels 1-5millimeters.
 18. The system of claim 14, further comprising: a sensorassociated with the panel-cleaner and configured to detect objects orfluid located on the photovoltaic panels; and a controller configured toexecute programmed instructions stored in a nontransitorycomputer-readable medium, wherein the instructions include: (i)obtaining data indicative of objects or fluid located on thephotovoltaic panels from the sensor; and (ii) automatically operatingthe first and second actuators and the panel-cleaner in response to thesensor detecting objects or fluid on the photovoltaic panels.
 19. Thesystem of claim 18, a remote mobile transmitter in communication withthe controller and configured to send a cleaning command to thecontroller to execute the instructions.